PERIPATRIC SPECIATION DRIVES DIVERSIFICATION AND DISTRIBUTIONAL PATTERN OF REEF HERMIT CRABS (DECAPODA: DIOGENIDAE: CALCINUS)

The diversity on coral reefs has long captivated observers. We examine the mechanisms of speciation, role of ecology in speciation, and patterns of species distribution in a typical reef‐associated clade—the diverse and colorful Calcinus hermit crabs—to address the origin of tropical marine diversity. We sequenced COI, 16S, and H3 gene regions for ～90% of 56 putative species, including nine undescribed, “cryptic” taxa, and mapped their distributions. Speciation in Calcinus is largely peripatric at remote locations. Allopatric species pairs are younger than sympatric ones, and molecular clock analyses suggest that >2 million years are needed for secondary sympatry. Substantial niche conservatism is evident within clades, as well as a few major ecological shifts between sister species. Color patterns follow species boundaries and evolve rapidly, suggesting a role in species recognition. Most species prefer and several are restricted to oceanic areas, suggesting great dispersal abilities and giving rise to an ocean‐centric diversity pattern. Calcinus diversity patterns are atypical in that the diversity peaks in the west‐central oceanic Pacific rather than in the Indo‐Malayan “diversity center.” Calcinus speciation patterns do not match well‐worn models put forth to explain the origin of Indo‐West Pacific diversity, but underscore the complexity of marine diversification.     

CHROMOSOMAL REARRANGEMENTS AND THE GENETICS OF REPRODUCTIVE BARRIERS IN MIMULUS (MONKEY FLOWERS)

Chromosomal rearrangements may directly cause hybrid sterility and can facilitate speciation by preserving local adaptation in the face of gene flow. We used comparative linkage mapping with shared gene‐based markers to identify potential chromosomal rearrangements between the sister monkeyflowers Mimulus lewisii and Mimulus cardinalis, which are textbook examples of ecological speciation. We then remapped quantitative trait loci (QTLs) for floral traits and flowering time (premating isolation) and hybrid sterility (postzygotic isolation). We identified three major regions of recombination suppression in the M. lewisii × M. cardinalis hybrid map compared to a relatively collinear Mimulus parishii × M. lewisii map, consistent with a reciprocal translocation and two inversions specific to M. cardinalis. These inferences were supported by targeted intraspecific mapping, which also implied a M. lewisii‐specific reciprocal translocation causing chromosomal pseudo‐linkage in both hybrid mapping populations. Floral QTLs mapped in this study, along with previously mapped adaptive QTLs, were clustered in putatively rearranged regions. All QTLs for male sterility, including two underdominant loci, mapped to regions of recombination suppression. We argue that chromosomal rearrangements may have played an important role in generating and consolidating barriers to gene flow as natural selection drove the dramatic ecological and morphological divergence of these species.     

Adaptive sympatric speciation of polychromatic "roundfin" sailfin silverside fish in Lake Matano (Sulawesi)

The significance of sympatric speciation is one of the most controversial topics in evolutionary biology. Theory suggests that different factors can lead to speciation in full geographical contact, including selection and nonrandom mating. Strict criteria have been established for assessing sympatric speciation, which have been met in only a very few cases. Here, we investigate differentiation among sympatric morphospecies and color morphs of "roundfin" sailfin silversides (Telmatherinidae), small freshwater fish endemic to ancient Lake Matano in Central Sulawesi (Indonesia). Morphospecies are distinct according to body shape (geometric morphometrics), population structure (population-level amplified fragment length polymorphism [AFLP] markers), ecology, and mating behavior (habitat transects, stomach contents). Explorative genome scans based on AFLPs indicate that divergent selection affects only 1.3-4.2% of the analyzed loci, suggesting an early stage of speciation. Transect data demonstrate strong assortative mating and adaptive niche differentiation. However, we find no restrictions in gene flow among the conspicuous male color morphs. In summary, our data are consistent with a sympatric mode of divergence among three morphospecies under conditions effectively ruling out allopatric scenarios. Substantial, but incomplete, reproductive isolation suggests an early stage of speciation, most likely due to ecological selection pressure.     

Oxovanadium(IV) and oxovanadium(V) complexes relevant to biological systems

A novel method for the analysis of trace element chemical speciation at parts per billion (ppb) levels in wound fluid samples both contributes to the fundamental inorganic biochemistry of the healing process and permits improved treatments. Potentiometric Stripping Analysis in combination with acid digestion has been used to quantify the total copper and zinc levels in a series of 0.5 ml samples of fluid obtained from surgical wounds. Further, the degree of blood contamination has been investigated using visible spectroscopy. The prevailing chemical speciation (chemical forms) of these total concentrations of copper and zinc amongst low molecular mass ligands in wound fluid has been investigated by computer modelling using JESS, the Joint Expert Speciation System. The model, involving 38 components, generates in the region of 3500 individual low molecular mass complexes including copper, zinc, iron, calcium and manganese species, and predicts that the majority of low molecular mass (lmm) copper complexes are electrically net-neutral, whilst those of zinc are predominantly charged. Further studies indicate that supplementing the concentrations of histidine and tryptophan may increase the net-neutral zinc fraction, the optimum effect being achieved at pH=7.4. This may be important in transporting zinc into healing cells.     

Lead phytoavailability change driven by its speciation transformation after the addition of tea polyphenols (TPs): Combined selective sequential extraction (SSE) and XANES analysis

Background and aims

Metal species in rhizosphere soil profoundly influence their mobility and phytoavailability. Clarifying the speciation transformation of heavy metals helps understand their translocation and accumulation in plants.

Methods

Single extraction, selective sequential extraction (SSE) and X-ray absorption near-edge structure (XANES) spectroscopy were employed to investigate the speciation transformation of lead (Pb) and its influence on metal accumulation in tea plants after the addition of tea polyphenols (TPs).

Results

Pb content was decreased in young leaves and stems, whereas increased in roots, after TPs were amended to soil. Both SSE and XANES analysis suggested bioavailable Pb was transformed to organically bound Pb after the addition of TPs. The increased percentage of organically bound Pb might be fixed in the cell wall of plant root through a ternary complex formed between the Pb-organic matter complex and cell wall components. Therefore, Pb translocation from roots to young tissues was decreased.

Conclusions

Pb phytoavailability change was driven by its speciation transformation after the addition of TPs. Combined SSE and XANES spectroscopy represent powerful tools to study metal speciation transformation in plant and soil systems.     

DEVELOPMENT OF PROTOPLASTS FROM HOLDFASTS AND VEGETATIVE THALLI OF MONOSTROMA LATISSIMUM (CHLOROPHYTA, MONOSTROMATACAE) FOR ALGAL SEED STOCK

The aim of this study was to isolate and cultivate the protoplasts of the green alga Monostroma latissimum Wittrock and subsequently induce them to form algal filaments to act as an algal "seed" stock. Protoplasts of the alga were isolated enzymatically with 4% cellulase Onozuka R-10 and 2% Macerozyme R-10. The highest number of protoplasts was obtained on a 50-rpm shaker with 1.2 M of sorbitol after 6 h of incubation, with a yield of 9 × 106 protoplasts·g−1 of fresh thallus (including holdfast). Protoplasts from both holdfasts and erect thalli usually began to form new cell walls within 5 h after isolation and began to divide from day 6 to day 9 in PES medium; cell clusters, filaments, and/or tubular thalli were formed from day 14 to day 18. For algae collected in March, about 60% of protoplasts isolated from vegetative thalli regenerated to form tubular thalli, and about 45% of protoplasts isolated from holdfasts regenerated to form filaments. However, for algae collected in May, about 1% of protoplasts isolated from vegetative thalli developed directly to form tubular thalli, and 59% of protoplasts regenerated to form cell clusters without the ability to differentiate, whereas protoplasts isolated from holdfasts failed to develop. Regenerated filaments were kept in an incubator for more than 3 years at 24° C under the low irradiance of 66μmol photons·m−2·s−1. After this time, they retained the ability to develop to form tubular thalli under irradiance of 166 and 300 μmol photons·m−2·s−1 at 18°–30° C. Subsequently, these tubular thalli can develop to form leafy thalli after being cultivated at high irradiance of 300 μmol photons·m−2·s−1 and at 18°–22° C. Therefore, the filaments could serve as"seed" stock for algal mass culture.     

EVOLUTION OF MIMICRY PATTERNS IN METRIORRHYNCHUS (COLEOPTERA: LYCIDAE): THE HISTORY OF DISPERSAL AND SPECIATION IN SOUTHEAST ASIA

The concept of Müllerian mimicry suggests convergent evolution to an intermediate pattern and does not predict polymorphism in mimicry rings. We examined the evolution of mimicry patterns and the order of divergence of various factors, including the role of aposematic patterns in speciation, in a clade of net-winged beetles with a robust phylogeny that suggests that they dispersed from the Australian to Asian plate. We found strong evidence for the evolution of mimicry via advergence in Metriorrhynchus because older patterns are represented in the Oriental region within more than 100 species of lycids from several lineages. Advergence was likely the cause of the observed intraspecific polymorphism in contrast to the predicted universal monomorphism. Polymorphism was found in populations of two species in Sumatra and Borneo and in populations fine-tuned to subtle variants in various habitats. The advergence is likely to be based on the small population sizes of immigrants. The differences in population sizes result in much higher benefits for dispersing species than native populations. Speciation was trigged by the divergence in aposematic coloration, and the genetic differences accumulated slowly during incomplete isolation. We assumed that the differentiation in genitalia through sexual selection ultimately reinforced speciation initiated by the shift between mimicry patterns.     

THE BEHAVIOUR AND BREEDING BIOLOGY OF THE SHETLAND WREN.

The behaviour of T. t. zetlandicus is shown to differ in several respects from that of T. t. troglodytes and, less markedly, from the behaviour of some other insular races. Attention is called to a type of behaviour which it is suggested should be called " transference activity". It is argued that there is a close connection between the availability of food for the nestlings and the character of the pair-bond, and that modifications in the integrative pattern of adaptations are of importance in speciation.     

Molecular phylogeny and biogeography of the dung beetle genus Temnoplectron Westwood (Scarabaeidae: Scarabaeinae) from Australia's wet tropics

The landscape of the Australian Wet Tropics can be described as "islands" of montane rainforest surrounded by warmer or more xeric habitats. Historical glaciation cycles have caused expansion and contraction of these rainforest "islands" leading to consistent patterns of genetic divergence within species of vertebrates. To explore whether this dynamic history has promoted speciation in endemic and diverse groups of insects, we used a combination of mtDNA sequencing and morphological characters to estimate relationships and the tempo of divergence among Australian representatives of the dung beetle genus Temnoplectron. This phylogenetic hypothesis shares a number of well-supported clades with a previously published phylogenetic hypothesis based on morphological data, though statistical support for several nodes is weak. Sister species relationships well-supported in both tree topologies, and a tree obtained by combining the two data sets, suggest that speciation has mostly been allopatric. We identify a number of speciation barriers, which coincide with phylogeographic breaks found in vertebrate species. Large sequence divergences between species emphasize that speciation events are ancient (pre-Pleistocene). The flightless, rainforest species appear to have speciated rapidly, but also in the distant past.     

COMPARATIVE PHYLOGEOGRAPHY OF A SIBLING PAIR OF RAINFOREST DROSOPHILA SPECIES (DROSOPHILA SERRATA AND D. BIRCHII)

Drosophila serrata and D. birchii are presumed sibling species; the former is a widespread generalist and the latter is restricted to rainforests. Comparison of the mtDNA sequence phylogeographies revealed two highly divergent, geographically distinct lineages of D. serrata that are as distinct from each other as either is from D. birchii. However, diversity in D. birchii is low and unstructured. The low diversity in D. birchii corresponds with a late-Pleistocene-Holocene contraction of lowland rainforests. We suggest that future studies of speciation and adaptation should compare the two lineages of D. serrata to each other as well as to D. birchii.     

The genus anemia (Schizaeaceae) in Mexico

The fern genusAnemia is represented in Mexico by 21 species and hybrids, of which five are here described as new:A. familiaris, A. multiplex. A. ×paraphyllitidis. A.×recondita andA. semihirsuta. Hybridization is frequent, resulting in both sterile and fertile hybrids, and has probably led to much recent speciation in the genus, including presumably sexual polyploids up to possibly the tetrakaidecaploid level.     

SINGLE FOUNDER-FLUSH EVENTS AND THE EVOLUTION OF REPRODUCTIVE ISOLATION

By demonstrating the evolution of significant premating isolation, previous laboratory experiments have provided some evidence for the founder-flush model of speciation. However, these experiments are subject to a number of criticisms, including the use of hybrid populations recently collected from the wild and the use of multiple bottlenecks. Here we present the results of a test of founder-flush speciation using a single, well-adapted laboratory stock of Drosophila melanogaster subjected to one founder-flush event. The experiment was replicated at larger scale than previous studies, and results indicate that none of 50 independent founder-flush lines evolved significant assortative mating relative to the control (base) population. This suggests a diminished emphasis on population bottlenecks in speciation of D. melanogaster and perhaps in general.     

BACULAR AND TESTICULAR GROWTH AND ALLOMETRY IN THE CAPE FUR SEAL ARCTOCEPHALUS P. PUSILLUS (OTARIIDAE)

The baculum in Arctocephalus p. pusillus reaches up to 14.1 cm in length, 13.5 g in mass, and 1.3 g/cm in density (= mass/length). A pubertal growth spurt occurs between 2 and 3 yr of age, when bacular length increases by 28%, mass by 124%, and density by 77%; concurrently, body length increases by 14%. A second, weaker spurt occurs at social maturity (9-10 yr of age). Testes grow most rapidly between 1 and 2 yr of age, when testicular length increases by 29%. After 3 yr of age, growth in bacular and testicular length slows, and bacular mass continues to increase approximately linearly. Bacular and testicular lengths average 6.8% and 3.4% (respectively) of body length in adults, compared with 9.9% and 5.7% in the promiscuous harp seal ( Pagophilus groenlandicus ). Bacular length, mass, and density, and testicular length, are positively allometric to body length over growth; bacular length is isometric to testicular length. Among animals of the same age, bacular length and mass are positively allometric to body length in young animals, with negative allometry or isometry thereafter; testicular length is isometric to body length in young animals and negatively allometric thereafter. Patterns of early growth and allometry of the baculum and testes are interpreted as adaptations for mating opportunities, years before territoriality is possible. The baculum and testes of adult Cape fur seals and other otariids are small compared with those of most phocids, because sperm competition among male otariids is weak.     

EVOLUTIONARY AND BIOGEOGRAPHIC ORIGINS OF HIGH TROPICAL DIVERSITY IN OLD WORLD FROGS (RANIDAE)

Differences in species richness between regions are ultimately explained by patterns of speciation, extinction, and biogeographic dispersal. Yet, few studies have considered the role of all three processes in generating the high biodiversity of tropical regions. A recent study of a speciose group of predominately New World frogs (Hylidae) showed that their low diversity in temperate regions was associated with relatively recent colonization of these regions, rather than latitudinal differences in diversification rates (rates of speciation–extinction). Here, we perform parallel analyses on the most species-rich group of Old World frogs (Ranidae; ∼1300 species) to determine if similar processes drive the latitudinal diversity gradient. We estimate a time-calibrated phylogeny for 390 ranid species and use this phylogeny to analyze patterns of biogeography and diversification rates. As in hylids, we find a strong relationship between the timing of colonization of each region and its current diversity, with recent colonization of temperate regions from tropical regions. Diversification rates are similar in tropical and temperate clades, suggesting that neither accelerated tropical speciation rates nor greater temperate extinction rates explain high tropical diversity in this group. Instead, these results show the importance of historical biogeography in explaining high species richness in both the New World and Old World tropics.     

GENOME DIVERGENCE AND THE GENETIC ARCHITECTURE OF BARRIERS TO GENE FLOW BETWEEN LYCAEIDES IDAS AND L. MELISSA

Genome divergence during speciation is a dynamic process that is affected by various factors, including the genetic architecture of barriers to gene flow. Herein we quantitatively describe aspects of the genetic architecture of two sets of traits, male genitalic morphology and oviposition preference, that putatively function as barriers to gene flow between the butterfly species Lycaeides idas and L. melissa. Our analyses are based on unmapped DNA sequence data and a recently developed Bayesian regression approach that includes variable selection and explicit parameters for the genetic architecture of traits. A modest number of nucleotide polymorphisms explained a small to large proportion of the variation in each trait, and average genetic variant effects were nonnegligible. Several genetic regions were associated with variation in multiple traits or with trait variation within‐ and among‐populations. In some instances, genetic regions associated with trait variation also exhibited exceptional genetic differentiation between species or exceptional introgression in hybrids. These results are consistent with the hypothesis that divergent selection on male genitalia has contributed to heterogeneous genetic differentiation, and that both sets of traits affect fitness in hybrids. Although these results are encouraging, we highlight several difficulties related to understanding the genetics of speciation.     

Trapping of lead (Pb) by corn and pea root border cells

Aims

Most plants produce a root tip extracellular matrix that includes viable border cell populations programmed to disperse into soil. Like neutrophils, border cells export structures that trap pathogens and prevent root tip infection. Border cells also trap metals. The goal of this study was to determine if border cells trap Pb.

Methods

Border cell responses to Pb were observed microscopically. Border cell impact on Pb-induced injury to roots was assessed using root growth assays. Pb removal from solution was measured using inductively coupled plasma mass spectrometry (ICP-MS). Speciation of Pb associated with border cells was evaluated by synchrotron X-ray absorption spectroscopy (XAS).

Results

Increased border cell trap size and number occurred within minutes in response to Pb but not silicon (Si). Transient immersion of root tips into Pb after border cells were removed resulted in growth inhibition. Immersion of root tips and border cells into Pb solution resulted in significant removal of Pb. Si levels in the presence of root tips remained unchanged. The Pb speciation, measured with Pb L_III XAS, altered when reacted with border cells, indicating that direct binding by extracellular traps occurred.

Conclusions

Border cells can trap Pb and prevent damage to the root tip.

     

寒武系小碳化石(SCFs)的研究进展及意义

所谓SCFs(Small Carbonaceous Fossils),可译为"小碳化石",其大小跨越了传统的微观与宏观界线(以肉眼可见与否为标准),是一个特定化石群体的统称。它的实质含义,是指通过氢氟酸(HF)等无机酸浸泡泥岩/页岩样品后经过滤、浓缩而获得的一类体积微小的有机碳质薄膜化石,包括后生动物残片、丝状藻/菌类碎片、疑源类等类型。在小碳化石概念被正式提出之前,国外学者曾先后用有机质壁微体化石(Organic-walled microfossils)、碳质微体化石(Carbonaceous microfossils)与布尔吉斯页岩型微体化石(Burgess Shale-type microfossils)来表述此类化石。目前在国际上,与布尔吉斯页岩型(BST)化石库和奥斯坦(Orsten)型化石库一样,小碳化石已经成为寒武纪古生物学及生物埋藏学等领域研究的一个重要的新窗口;同时,通过三类特异埋藏化石的对比研究,实现优势互补,从而能够更好地阐述早期生物的演化与多样性。     

Synthesis, structural, spectroscopic and magnetic susceptibility studies of a soluble Cr(III)-heida (2-hydroxyethyliminodiacetic acid) complex. Relevance to aqueous chromium(III)-heida speciation

In order to delineate the interactions of Cr(III) with low molecular mass ligands, often involved in chemistries of toxic and/or biologically significant processes, the aqueous structural speciation of the binary Cr(III)-heida (2-hydroxyethyliminodiacetic acid) system was investigated. The reaction of Cr(NO₃)₃ · 9H₂O with heida at a specific pH (5.5) led to the isolation of a red crystalline (NH₄)[Cr{HOCH₂CH₂N(CH₂COO)₂}₂] · 2H₂O (1), which was characterized by elemental analysis, spectroscopic, structural, thermal, and magnetic susceptibility studies. The structure of 1 reveals a mononuclear octahedral complex of Cr(III) with two doubly ionized heida ligands bound to it. The ligand alcoholic side chains do not participate in metal binding and dangle away from the complex. The structural and spectroscopic data emphasize the physicochemical properties of 1 in the solid state and in solution, thus reflecting the profile of 1 in the overall aqueous structural speciation scheme of the Cr(III)-heida system. The employed pH-specific synthetic endeavor exemplifies (a) the potential utility of the strategy in the exploration of key structural and chemical attributes of soluble aqueous species, arising from the biologically relevant interactions of Cr(III) with the O,N-containing ligands, and (b) the potential linkage of the chemical reactivity of Cr(III) toward the O,N-containing substrates of a variable structural composition with physiological processes or toxicity events.     

中国特有金线鲃属鱼类研究的回顾与展望(鲤形目,鲤科)

金线鲃属鱼类是中国特有类群,几乎所有种类的生息繁衍都离不开洞穴环境,由于洞穴间的隔离作用,属内物种分化十分强烈.本文对以往有关金线鲃属的研究进行了回顾,将其研究历程分为5个不同阶段:发现期、静默期、恢复期、快速发展期和深入研究期,每个阶段都有不同的特点和代表性工作.以往的研究以分类学为主,向传统分类和系统分类两个方向开展.目前金线鲃属鱼类研究还存在一系列问题以及研究空白.未来有关的研究可在物种演化、生态学、生理学、行为学和保护生物学等多个方面深入进行.     

A CLADISTIC ANALYSIS OF THE EVOLUTION AND BIOGEOGRAPHY OF DURVILLAEA (PHAEOPHYTA)1

The genus Durvillaea currently has four recognized species found along many exposed, rocky coastlines of the temperate to sub-Antarctic regions in the Southern Hemisphere. We propose that the current species distributions are related primarily to vicariance events and subsequent speciation associated with the breakup of Gondwana between 40 and 100 Ma. From an ancestral species, a stipitate species developed in the Tasman basin, with separation and speciation resulting in the D. potatorum/ D. willana complex in southeastern Australia and New Zealand. A second line of evolution led to D. chathamensis and D. antarctica characterized by a honeycombed medulla. The extensive distribution of D. antarctica throughout the Southern Hemisphere is related to both vicariance and dispersal events. The status of D. chathamensis as a species distinct from D. antarctica is questioned. The affinities of an as yet undescribed taxon from the Antipodes Islands are thought to be with the D. potatorum complex but require further study before they can be defined more precisely .